Developing a flexible range sensing system for industrial inspection applications

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Abstract

This thesis describes the development of a range sensing system. The goal was to
create a range sensor that is robust and flexible so that a number of applications within the
forest products manufacturing environment can be addressed. Features of the system
include: the capability of producing spatially registered image pairs of range and intensity,
the ability to generate both range and intensity very quickly, the applicability to a wide
variety of industrial applications, the ability to handle large depth-of-field range sensing
problems, the ability to do real-time data processing, and the capability to do extensive
system diagnostics under complete software control.

A triangulation based plane-of-light optical method is employed to extract range
information. The research shows that this method suits range sensing applications where
conveyor belts are involved. An in-depth study of the triangulation method is included. In
the study it shows that this method also supports large depth-of-field range sensing. A
dedicated signal processing hardware, built on the Micro Channel interface, performs
pipelined image processing and generates range and intensity images in a spatially
registered form. The hardware is designed to support several modes of operation, for the
purpose of facilitating optical adjustments and calibrations. The hardware self-diagnostic
facility is also included in the design.
A

memory management scheme is provided that facilitates real-time data
processing of the range and intensity images. The experiments show that this scheme
provides a real-time environment for software processing. This thesis also contains a
theory exploring the limitations of the measurement accuracy of the range detection
algorithm employed in the prototype system.
The maximum data generation rate of the prototype system is 380 range/intensity
lines per second at 128 range/intensity pixels per line. Several proposals toward future
work are included that aim at improving the speed as well as the measurement accuracy of
the prototype system.